Complex emergencies

Complex emergencies are situations of disrupted livelihoods and threats to life produced by warfare, civil disturbance and large-scale movements of people, in which any emergency response has to be conducted in a difficult political and security environment.
Environmental health in emergencies and disasters: a practical guide(WHO, 2002)

Complex emergencies combine internal conflict with large-scale displacements of people, mass famine or food shortage, and fragile or failing economic, political, and social institutions. Often, complex emergencies are also exacerbated by natural disasters.

WHO's response to complex emergencies is coordinated by the department of Health Action in Crisis.